c4_qam.m

QAM调制的ＭＡＴＬＡＢ程序仿真

%file: c4_qamdemo.m
levelx=input('Number of D levels>');
levely=input('Number of Q levels>');
m=input('Number of symbols>');
n=input('Number of samples per symbol>');
bw=input('Filter bandwidth,0<bw<1,>');
[xd,xq]=qam(levelx,levely,m,n);
[b,a]=butter(6,bw);%determine filter coefficients
yd=filter(b,a,xd);
yq=filter(b,a,xq);
subplot(2,2,1)
plot(xd,xq,'o')
a=1.4;
maxd=max(xd);maxq=max(xq);
mind=min(xd);minq=min(xq);
axis([a*mind a*maxd a* minq a*maxq])
axis equal;
xlabel('xd');ylabel('xq');
subplot(2,2,2)
plot(yd,yq)
axis equal;
xlabel('yd');ylabel('yq');
sym=30;
nsym=(0:sym*n)/n;
subplot(2,2,3)
plot(nsym(1:sym*n),yd(1:sym*n))
xlabel('symbol index');
ylabel('xd');
subplot(2,2,4)
plot(nsym(1:sym*n),yq(1:sym*n))
xlabel('symbol index');
ylabel('xq');
%End of  script file